The objective of the Head Injury Biostatistics Center is to provide necessary biostatistical services to all investigators in the proposed projects. As a core facility, the Biostatistics Center will coordinate, monitor, analyze and report throughout all phases of the proposed clinical trials and other studies. In particular, the Biostatistics Center will collaborate with investigators with respect to experimental design, sample size requirements, data entry forms, data management for both Richmond and Maryland centers, statistical analysis, interpretation of the results, conclusions and documentations. For the past ten years, the Biostatistics Center has been an important resource to all investigators in these respects. In addition to frequent meetings with individual investigators, our two regular weekly meetings for clinical researchers and basic scientists keep the collaboration close. In addition, Dr. Choi meets regularly with many principal investigators to advise and assist them in monitoring quantitative aspects of all projects. The research proposals submitted here indicate the collection of large amounts of data, and the collaboration of biostatisticians with investigators is important at all phases of the study, from design to conclusion. Statistical analyses will be custom-tailored to each project, and some may well require the development of new statistical methods. Some of the more useful statistical methods used in the Head Injury program during the last five years include various types of analysis of variance, correlation and regression, logistic regression, various multivariate analysis, and predictive probability analysis. The Biostatistics Center is invaluable to the proposed program.